Putty into the 871 Router
Run the command “Show Run” to start scrolling through and get the outside IP Interface, IP Address and Subnet Mask.
ip address %CurrentIPAddress% %CurrentIPSubnet%
Scroll further and get the IP Route (Gateway Address)
ip route 0.0.0.0 0.0.0.0 %CurrentGatewayIP%
Prpare a short script to remove the old ISP settings and add the new ISP settings.
Start with the Gateway (IP ROUTE).
Example below between the hypens.e
no ip route 0.0.0.0 0.0.0.0 %CurrentGatewayIP%
ip route 0.0.0.0 0.0.0.0 %NewGatewayIP%
no ip address %CurrentIPAddress% %CurrentIPSubnet%
ip address %NewIPAddress% %NewIpAddressSubnet%
Run the command “Conf T”
Copy and paste entire script into Putty.
Once internet is verified up and running, “Exit” out of Config mode.
Run the command “Write Mem“